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Friday, 9 October

JEE Main 2026 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 6 April 2026, Shift 2, Physics Q45

Question 45 of 75 in this shift, Physics question 20 of 25, Section A.

In a Young double slit experiment, the wavelength of incident light is 6000 Å, the separation between slits S1S_1 and S2S_2 is 5 cm and the distance between slits plane and screen is 50 cm, as shown in the figure below. If the resultant intensity at PP is equal to the intensity due to individual slits, the path difference between interfering waves is __________ Å.

The figure, in words

Young double-slit set-up: source S (λ = 6000 Å) on the left, slits S1 (upper) and S2 (lower) on a vertical plane, screen at distance 50 cm marked with O' on the central axis and point P below O' on the screen; rays drawn from S to both slits and from both slits to P.
  1. (1)4000Official answer
  2. (2)3000
  3. (3)2000Official answer
  4. (4)1000

Official answer

Options 1 and 3

NTA final key: multiple options accepted. Either option scored full marks.

Chapter
Wave Optics
Topic
Young's Double Slit
Idea tested
Intensity at Fractional Path Differences

Same idea in other shifts

Asked 5× in all
  1. 2 Apr 2026, Shift 2 · Q46In a Young's double slit experiment, the intensity at some point on the screen is found to be 34\frac{3}{4} times of the maximum of the…MediumNumerical value
  2. 6 Apr 2026, Shift 1 · Q36In interference experiment the path difference between two interfering waves at a point AA on the screen is λ/3\lambda/3, where λ\lambda…EasySingle correct
  3. 9 Apr 2024, Shift 1 · Q59In a Young's double slit experiment, the intensity at a point is (14)th\left(\frac{1}{4}\right)^{th} of the maximum intensity, the minimum…MediumNumerical value
  4. 6 Sep 2020, Shift 2 · Q24A Young's double-slit experiment is performed using monochromatic light of wavelength λ\lambda. The intensity of light at a point on the…MediumNumerical value

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.